Process of manufacturing paper



Patented Nov. 8, 1927.

UNITED STATES PATENT/OFFICE...

ARTHUR E. BARNARD AND ROBERT G. .CASWELL, 'OF NEWTON, MASSACHUSETTS, AS-

SIGNORS TO W. B. PRATT, INCH, OF NEWTONVILLE, MASSACHUSETTS, A CORPORA- TION OF MASSACHUSETTS.

I PROCESS OF MANUFACTURING PAPER.

No Drawing.

The object of this invention is to produce a paper from any of. the usual cellulos1c paper-making materials, e. g. chemical wood pulp, but having a strength exceedlng that of paper made from such materials by the ordinary or usual processes.

We have discovered that, if the pulp be beaten or milled in the presence of certain alkalies prior to the formation of the pulp into a web, a sheet may beformed which 'when dried has a bursting strength greatly the proportion of ammonia contained in the I water, or with the concentration of ammonia, the time of beating being constant in each case. For example, an increase of 1% in the bursting strength of paper produced from sulphate pulp has been noted when the Water contains 0.005% of ammonia; and, where the water contains0.05% of ammonia, equivalent to 0.1% of NH based on the amount of u1p beaten, we have noted an increase in bursting strength of about 7%. The figures which are herein given are only average figures resulting from a number of- In actual commercial operation, de-

tests.

. pending ppon the results desired to be secured, the water may contain from about 0.05% to more than 0.2% ammonia, based on weight, (or about 0.1% to 4% of NH, based on weight of dry'pulp) and in the case of thewatercontaining 0.2% ammonia, the average of a number of tests has shown an increase in strength of about 23% over paper produced from sulphate pulp under the same conditions but lacking ammonia in the beating water.

In preparin the water for the beating operation, there is added thereto suflicient aqua ammonia having a predetermined NH, content so as to give to the beating water the desired alkalinity. Although the bursting strength of the paper is increased as herein set forth, there 1s no increase in the shrink- Application filed July 30, 1923. Serial No. 654,778.

age in area of paper thus formed over paper made under identical conditions but lacking the presence of ammonia in the water. In stead of using NH in the form of aqua ammonia, we may employ an ammonium salt, such as ammonium carbonate, with comparable results. For example, by employment of ammonium carbonate,

in an amount which is the equivalent of 0.2% NH we have secured an increase in the bursting strength averaging 19.48%.

We have made the further discovery that if to the diluted pulp, after being beaten with the ammoniated water, there be added certain soluble metallic salts, the bursting strength of the paperis further surprisingly increased. For this purpose we have successfully used the sulphates of aluminum, copper and zinc, with a further average increase in bursting strength of over 25%. In

carrying out this step of .our process, the dilution of the pulp is effected. by the addition of ammoniated water of sufficient concentration so that the water in the pulp has a concentration of about 0.1% NH To the diluted pulp is now added suflicient soluble salt, such as sulphate of aluminum, copper or mm, to react with the ammonia. For example, when aluminum sulphate is used for the purpose,'it is added in excess of that amount which would be required for the formation of aluminite, .or basic aluminum sulphate soi+mio Al-0H \OH When sulphate of copper is employed for the purpose, a suflicient quantity is added to form'with the ammonia, cupric hydroxide. Onthe other hand, where zinc sulphate is added to the diluted pulp, a sufiicient quantity is employed to form the hydroxide of zinc. (and in fact necessary) to increase the quantity or amount of the ammonia in the beater contents at the end of the beating operation, as the proportion of ammonia would otherwise be insufiicient for reaction with the added soluble salts to produce a sutiicient amount of the above-mentioned salts to In these operations, it is desirable secure the desired increase in bursting strength. We do not regard the use of the sulphates of copper and zinc as desirable as the use of aluminum sulphate, for the reason that there is a marked increase inthe area shrinkage of the paper, even though its bursting strength is increased. Moreover, it

is to be noted that, due to the increase in the weightof the resulting paper, the bursting strength in relation tothe weight is not as great when sulphates of copper and zinc are employed as where aluminum sulphate is employed.

What we claim is 1. The herein described process of producing paper having an increased bursting stren th, which comprises beating or milling cellu ose pulp to effect the hydration thereof in the resence of ammonia, in' conditioning the pu p for the web formation.

2. The herein described process of treating cellulosic pulp for the manufacture of paper having an increased strength, which comprises beating or milling such pulp to effect the hydration thereof in ammoniated water having a concentration of appronimately 0.001% to and above 0.2% ammonia.

3. The herein described process of treating cellulosic pulp in the formation of pa presence of ammonia, and then adding ahi minum sulphate.

5. The herein described process of treati'ng cellulosic pulp in the formation of paper, which comprises beating the cellulosic pulp to effect the hydration. thereof in the presence of ammonia, increasing the ammon'iacontent of the pulp after beating, and

then adding a soluble metallic salt.

In testimony whereof we have affixed our signatures.

ARTHUR E. BARNARD. ROBERT GASWEL L. 

